Spacing requirements of 0.7 in. (18 mm) diameter prestressing strands

Dang, Canh N.; Floyd, Royce W.; Hale, William; Martí‐Vargas, José R.

doi:10.15554/pcij.01012016.70-87

Cited by 12 publications

(4 citation statements)

References 20 publications

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“…Their (Hegger and Bertram 2008a, b) results are similar to the values of transfer lengths obtained in the current study. However, in accordance with Dang et al (2016a), the transfer length of the strand in high-strength concrete (HSC) with a 28-day compressive strength equal to or higher than 69 MPa ranged from 500 to 730 mm, which was much higher than that of UHPFRC. Thus, it can be noted that prestressing strands embedded in UHPFRC exhibited much shorter transfer lengths compared with those embedded in ordinary HSC.…”

Section: Transfer Lengthmentioning

confidence: 82%

“…It is obvious that the previous ACI 318 and AASHTO LRFD codes significantly overestimate the transfer length of strands embedded in UHPFRC, whereas the Eurocode 2 slightly underestimated it. Similarly, Dang et al (2016a) reported that the codes overestimated the transfer length of strands embedded in HSC: approximately 1.22-1.78 and 1.47-2.14 times higher transfer lengths were calculated by the ACI 318 and AASHTO LRFD codes, respectively, as compared to the test data. In the case of UHPFRC, the ACI 318 code overestimated the transfer length as 2.14-2.63, while the AASHTO LRFD code overestimated it as 2.57-3.16, which were higher than those for HSC.…”

Section: Transfer Lengthmentioning

confidence: 84%

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Bond Behavior of Pretensioned Strand Embedded in Ultra-High-Performance Fiber-Reinforced Concrete

Shin

Lee

Yoo

2018

Int J Concr Struct Mater

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This study aimed to investigate the bond properties of prestressing strands embedded in ultra-high-performance fiberreinforced concrete (UHPFRC). Toward this end, two types of prestressing strands with diameters of 12.7 and 15.2 mm were considered, along with various concrete cover depths and initial prestressing force magnitudes. The average bond strength of the strands in UHPFRC was estimated by using pullout tests, and the transfer length was evaluated based on a 95% average maximum strain method. Test results indicated that the average bond strength of the pretensioned strand reduced as the diameter of the strand increased, and was between the bond strengths of round and deformed steel rebars. Higher bond strength was also obtained with a lower embedment length. Based on a comparison of p value, the bar diameter and embedment length most significantly influenced the bond strength of strands in UHPFRC, compared to a ratio of cover depth to diameter and initial prestressing force. Pretensioned strands in UHPFRC exhibited much higher bond strength and shorter transfer length compared with strands embedded in ordinary high-strength concrete. Lastly, ACI 318 and AASHTO LRFD codes significantly overestimated the transfer length of the strands embedded in UHPFRC.

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Section: Transfer Lengthmentioning

confidence: 82%

Section: Transfer Lengthmentioning

confidence: 84%

Bond Behavior of Pretensioned Strand Embedded in Ultra-High-Performance Fiber-Reinforced Concrete

Shin

Lee

Yoo

2018

Int J Concr Struct Mater

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“…18‐mm (0.7 in.) diameter strand is attractive due to its larger strength capacity . However, International Federation for Structural Concrete, ACI 318, and AASHTO LRFD do not provide any guidance on the bond of this strand.…”

Section: Research Significancementioning

confidence: 99%

Pretensioned pullout test of 18 mm (0.7 in.) diameter strand with different embedment lengths

Xin

Gui

John

2019

Structural Concrete

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In this paper, a pretensioned pullout test method was proposed to better understand the bond mechanism and evaluate the bond behavior of pretensioned concrete members. A total of 15 pullout specimens with a centered 18‐mm (0.7 in.) diameter strand were tested. The specimens were divided into three sets according to their strand embedment lengths. For each set, there are two non‐pretensioned specimens and three pretensioned specimens with different initial prestress levels. In this way, the effects of the strand embedment length and the pretension level on the bond behavior were studied, in terms of the development of strand slip subject to the pullout force, initial P–S slope, the distribution of concrete surface strain, the ultimate failure mode and the pullout energy. The experimental results verified that the strand transfer length was dependent of prestress level. The transfer length may be predicted based on the different level of effective pretension force or stress in pretensioned specimens with different strand embedment lengths at detensioning. In essence, the disparities of the bond behaviors in the tests were caused by the contributions of different bond mechanisms. In return, the former, especially the characteristics of the development of strand slip and pullout energy, may be used for the quantificational evaluation of the bond mechanisms. Hoyer effect is verified as the dominant bond mechanism within transfer length.

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“…In the current practice, a number of new types of concrete and prestressing strand are used for precast, prestressed concrete applications. Self-consolidating concrete (SCC) and lightweight SCC (Bymaster et al, 2015) and increased strand diameter (Dang et al, 2016b(Dang et al, , 2016c; Maguire et al, 2013;Morcous et al, 2014;Song et al, 2013) are recent developments in the concrete industry. However, when compared with a normal-weight, non-SCC mixture, a greater amount of paste in SCC or a lower stiffness of aggregates in lightweight SCC can weaken the strand-concrete bond (Burgueño and Haq, 2007;Floyd et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Prediction of development length from free-end slip in pretensioned concrete members

Dang

Floyd

Hale

et al. 2018

Magazine of Concrete Research

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Development length of prestressing strands is a significant parameter in the design of pretensioned concrete members. The adequacy of the code equations used to predict the development length needs to be verified when a new material or design parameter is introduced for precast, prestressed concrete applications. This study develops a simple and reliable technique to quantify the development length based on the premise of the slip theory, which proposes the free-end slip (FES) as an indicator of the development length. Twenty-five pretensioned concrete beams were cast with 15 mm diameter strands. FES was measured at both beam ends at prestress transfer. Development length was determined by performing bending tests at different embedment lengths. The experimental results were synthesised to revise the slip theory. The applicability of the revised-slip theory was validated by collected experimental data of pretensioned concrete members using various types of concrete, strand diameters and release techniques. Cite this articleDang CN, Floyd RW, Hale WM and Martí-Vargas JR (2018) Prediction of development length from free-end slip in pretensioned concrete members. Magazine of Concrete Research 70 (14): 714-725, https://doi.

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Spacing requirements of 0.7 in. (18 mm) diameter prestressing strands

Cited by 12 publications

References 20 publications

Bond Behavior of Pretensioned Strand Embedded in Ultra-High-Performance Fiber-Reinforced Concrete

Bond Behavior of Pretensioned Strand Embedded in Ultra-High-Performance Fiber-Reinforced Concrete

Pretensioned pullout test of 18 mm (0.7 in.) diameter strand with different embedment lengths

Prediction of development length from free-end slip in pretensioned concrete members

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